/*
 * Swipe 2.0
 *
 * Brad Birdsall
 * Copyright 2013, MIT License
 *
*/
define(function(){
  function Swipe(container, options) {

    "use strict";

    // utilities
    var noop = function() {}; // 简单的无操作功能
    var offloadFn = function(fn) { setTimeout(fn || noop, 0) }; // 卸载功能的执行
    
    // 检查浏览器的功能
    var browser = {
      addEventListener: !!window.addEventListener,
      touch: ('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch,
      transitions: (function(temp) {
        var props = ['transformProperty', 'WebkitTransform', 'MozTransform', 'OTransform', 'msTransform'];
        for ( var i in props ) if (temp.style[ props[i] ] !== undefined) return true;
        return false;
      })(document.createElement('swipe'))
    };

    // 如果没有根元素退出
    if (!container) return;
    var element = container.children[0];
    var slides, slidePos, width;
    options = options || {};
    var index = parseInt(options.startSlide, 10) || 0;
    var speed = options.speed || 300;
    options.continuous = options.continuous ? options.continuous : true;

    function setup() {

      // 缓存的幻灯片
      slides = element.children;

      //创建一个数组来存储每个幻灯片的当前位置
      slidePos = new Array(slides.length);

      // 确定每个幻灯片的宽度
      width = container.getBoundingClientRect().width || container.offsetWidth;

      element.style.width = (slides.length * width) + 'px';

      // 栈元素
      var pos = slides.length;
      while(pos--) {

        var slide = slides[pos];

        slide.style.width = width + 'px';
        slide.setAttribute('data-index', pos);

        if (browser.transitions) {
          slide.style.left = (pos * -width) + 'px';
          move(pos, index > pos ? -width : (index < pos ? width : 0), 0);
        }

      }

      if (!browser.transitions) element.style.left = (index * -width) + 'px';

      container.style.visibility = 'visible';

    }

    function prev() {

      if (index) slide(index-1);
      else if (options.continuous) slide(slides.length-1);

    }

    function next() {

      if (index < slides.length - 1) slide(index+1);
      else if (options.continuous) slide(0);

    }

    function slide(to, slideSpeed) {

      // 如果已经滑不要求
      if (index == to) return;
      
      if (browser.transitions) {

        var diff = Math.abs(index-to) - 1;
        var direction = Math.abs(index-to) / (index-to); // 1:right -1:left

        while (diff--) move((to > index ? to : index) - diff - 1, width * direction, 0);

        move(index, width * direction, slideSpeed || speed);
        move(to, 0, slideSpeed || speed);

      } else {

        animate(index * -width, to * -width, slideSpeed || speed);

      }

      index = to;

      offloadFn(options.callback && options.callback(index, slides[index]));

    }

    function move(index, dist, speed) {

      translate(index, dist, speed);
      slidePos[index] = dist;

    }

    function translate(index, dist, speed) {

      var slide = slides[index];
      var style = slide && slide.style;

      if (!style) return;

      style.webkitTransitionDuration = 
      style.MozTransitionDuration = 
      style.msTransitionDuration = 
      style.OTransitionDuration = 
      style.transitionDuration = speed + 'ms';

      style.webkitTransform = 'translate(' + dist + 'px,0)' + 'translateZ(0)';
      style.msTransform = 
      style.MozTransform = 
      style.OTransform = 'translateX(' + dist + 'px)';

    }

    function animate(from, to, speed) {

      // 如果不是动画，只是重新定位
      if (!speed) {
        
        element.style.left = to + 'px';
        return;

      }
      
      var start = +new Date;
      
      var timer = setInterval(function() {

        var timeElap = +new Date - start;
        
        if (timeElap > speed) {

          element.style.left = to + 'px';

          if (delay) begin();

          options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);

          clearInterval(timer);
          return;

        }

        element.style.left = (( (to - from) * (Math.floor((timeElap / speed) * 100) / 100) ) + from) + 'px';

      }, 4);

    }

    // 安装程序自动幻灯片
    var delay = options.auto || 0;
    var interval;

    function begin() {

      interval = setTimeout(next, delay);

    }

    function stop() {

      delay = 0;
      clearTimeout(interval);

    }


    // 设置初始变量
    var start = {};
    var delta = {};
    var isScrolling;      

    // 设置事件捕获
    var events = {

      handleEvent: function(event) {

        switch (event.type) {
          case 'touchstart': this.start(event); break;
          case 'touchmove': this.move(event); break;
          case 'touchend': offloadFn(this.end(event)); break;
          case 'webkitTransitionEnd':
          case 'msTransitionEnd':
          case 'oTransitionEnd':
          case 'otransitionend':
          case 'transitionend': offloadFn(this.transitionEnd(event)); break;
          // case 'resize': offloadFn(setup.call()); break;
        }

        if (options.stopPropagation) event.stopPropagation();

      },
      start: function(event) {

        var touches = event.touches[0];

        // 测量的起始值
        start = {

          // 得到初始的触摸坐标
          x: touches.pageX,
          y: touches.pageY,

          // 存储时间确定接触时间
          time: +new Date

        };
        
        // 用于测试的第一移动事件
        isScrolling = undefined;

        // 复位三角洲和最后计算值
        delta = {};

        // 设置touchmove和touchend监听
        element.addEventListener('touchmove', this, false);
        element.addEventListener('touchend', this, false);

      },
      move: function(event) {

        // 确保一个触摸不捏刷
        if ( event.touches.length > 1 || event.scale && event.scale !== 1) return

        if (options.disableScroll) event.preventDefault();

        var touches = event.touches[0];

        // 计算改变后的 x 和 y
        delta = {
          x: touches.pageX - start.x,
          y: touches.pageY - start.y
        }

        // 确定测试运行——一个滚动时间测试
        if ( typeof isScrolling == 'undefined') {
          isScrolling = !!( isScrolling || Math.abs(delta.x) < Math.abs(delta.y) );
        }

        // 如果用户没有试图垂直滚动
        if (!isScrolling) {

          // 防止本机滚动
          event.preventDefault();

          // 停止幻灯片显示 
          stop();

          // 如果第一个或最后一个滑动阻力增加
          delta.x = 
            delta.x / 
              ( (!index && delta.x > 0               // if first slide and sliding left
                || index == slides.length - 1        // or if last slide and sliding right
                && delta.x < 0                       // and if sliding at all
              ) ?                      
              ( Math.abs(delta.x) / width + 1 )      // determine resistance level
              : 1 );                                 // no resistance if false
          
          // 转化 1:1
          translate(index-1, delta.x + slidePos[index-1], 0);
          translate(index, delta.x + slidePos[index], 0);
          translate(index+1, delta.x + slidePos[index+1], 0);

        }

      },
      end: function(event) {

        // 计算持续时间
        var duration = +new Date - start.time;

        // 确定滑动尝试触发下一个/上一页滑动
        var isValidSlide = 
              Number(duration) < 250               // if slide duration is less than 250ms
              && Math.abs(delta.x) > 20            // and if slide amt is greater than 20px
              || Math.abs(delta.x) > width/2;      // or if slide amt is greater than half the width

        // 如果尝试确定滑过去的开始和结束
        var isPastBounds = 
              !index && delta.x > 0                            // 如果第一个幻灯片和幻灯片AMT大于0
              || index == slides.length - 1 && delta.x < 0;    // 或者如果最后一张幻灯片,幻灯片amt小于0
        
        // 确定滑动方向(true:right, false:left)
        var direction = delta.x < 0;

        // 如果不垂直滚动
        if (!isScrolling) {

          if (isValidSlide && !isPastBounds) {

            if (direction) {

              move(index-1, -width, 0);
              move(index, slidePos[index]-width, speed);
              move(index+1, slidePos[index+1]-width, speed);
              index += 1;

            } else {

              move(index+1, width, 0);
              move(index, slidePos[index]+width, speed);
              move(index-1, slidePos[index-1]+width, speed);
              index += -1;

            }

            options.callback && options.callback(index, slides[index]);

          } else {

            move(index-1, -width, speed);
            move(index, 0, speed);
            move(index+1, width, speed);

          }

        }

        // 取消touchmove和touchend事件监听器,直到touchstart再次调用
        element.removeEventListener('touchmove', events, false)
        element.removeEventListener('touchend', events, false)

      },
      transitionEnd: function(event) {

        if (parseInt(event.target.getAttribute('data-index'), 10) == index) {
          
          if (delay) begin();

          options.transitionEnd && options.transitionEnd.call(event, index, slides[index]);

        }

      }

    }

    // 触发设置 
    setup();

    // 如果适用则开始自动幻灯片
    if (delay) begin();


    // 添加事件监听器
    if (browser.addEventListener) {
      
      // 设置touchstart事件元素    
      if (browser.touch) element.addEventListener('touchstart', events, false);

      if (browser.transitions) {
        element.addEventListener('webkitTransitionEnd', events, false);
        element.addEventListener('msTransitionEnd', events, false);
        element.addEventListener('oTransitionEnd', events, false);
        element.addEventListener('otransitionend', events, false);
        element.addEventListener('transitionend', events, false);
      }

      //设置在窗口调整大小事件
      window.addEventListener('resize', events, false);

    } else {

      window.onresize = function () { setup() }; // to play nice with old IE

    }

    // 公开Swipe API
    return {
      setup: function() {

        setup();

      },
      slide: function(to, speed) {

        slide(to, speed);

      },
      prev: function() {

        // cancel slideshow
        stop();

        prev();

      },
      next: function() {

        stop();

        next();

      },
      getPos: function() {

        // return current index position
        return index;

      },
      kill: function() {

        // 取消幻灯片
        stop();

        // reset element
        element.style.width = 'auto';
        element.style.left = 0;

        // reset slides
        var pos = slides.length;
        while(pos--) {

          var slide = slides[pos];
          slide.style.width = '100%';
          slide.style.left = 0;

          if (browser.transitions) translate(pos, 0, 0);

        }

        // 删除事件侦听器
        if (browser.addEventListener) {

          // remove current event listeners
          element.removeEventListener('touchstart', events, false);
          element.removeEventListener('webkitTransitionEnd', events, false);
          element.removeEventListener('msTransitionEnd', events, false);
          element.removeEventListener('oTransitionEnd', events, false);
          element.removeEventListener('otransitionend', events, false);
          element.removeEventListener('transitionend', events, false);
          window.removeEventListener('resize', events, false);

        }
        else {

          window.onresize = null;

        }

      }
    }
  }
  if ( window.jQuery || window.Zepto ) {
    (function($) {
      $.fn.Swipe = function(params) {
        return this.each(function() {
          $(this).data('Swipe', new Swipe($(this)[0], params));
        });
      }
    })( window.jQuery || window.Zepto )
  }
  return Swipe;
});

